1. Technical Field
This invention relates to magnetic recording media and servo systems for magnetic recording heads and more particularly to magnetic recording disks including optical servo information on the disks and control systems for positioning magnetic read/write heads cooperating therewith.
2. Background Art
Schneider, "Optical Servo Information on Magnetic Recording Disks," IBM Technical Disclosure Bulletin, 16 No. 4, 1082 (Sept. 1973), shows a slider carrying a pair of lasers and detectors which sense cams 9 that form a track on the magnetic disk.
Koshino et al "Optical Method of Head Positioning in Magnetic Disk Systems," IEEE Trans. on Magnetics, MAG-16 No. 5, 631-633 (Sept. 1980), shows an aluminum substrate covered with tracks of black colored dye. The magnetic coated film is carried on top of the substrate containing alternating colored and noncolored layers. It is required for optical fibers to connect the LED on the arm with the head core on the slider.
Kruger, U.S. Pat. No. 4,123,788 for "Magnetic Information Carrier with Optical Servo Tracks and Apparatus for Reading and Writing the Same" shows a medium with optical servo tracks in which the magnetic recording medium is deposited upon a reflective layer so that when a laser beam burns away the magnetic layer, a reflective pattern is formed permitting servo information to be read. Kruger uses an optical fiber sensor using an LED and photodiodes. There were tracks of black dye placed upon the substrate. Alternatively, the servo data can be added by photolithography.
Acosta et al, "Floppy Disk Embossing for Servo Applications," IBM Technical Disclosure Bulletin, 21, pp. 4259-60, (March 1979), describes mechanical tracks embossed in a disk.